This application is directed to a catheter assembly, and particularly an electrophysiology/ablation catheter of the type used for diagnostic and therapeutic medical procedures. It finds particular application in minimally invasive cardiac electrophysiology studies such as cardiac diagnostic or ablation procedures in which precise and controlled movement of conductive electrodes provided on a distal portion of the catheter are required.
It is known from commonly owned U.S. Pat. Nos. 5,552,713 and 5,861,024 to provide an electrophysiology/ablation catheter to monitor and record intra-cardiac electrical signals. The details of these patents are expressly incorporated herein by reference. The electrical signals from the heart are conducted through the electrodes to associated monitoring and recording devices. The electrodes can also be used, for example, to deliver energy to the heart either as a stimulus to monitor the heart's response thereto or to deliver energy for ablation procedures if required.
As will be appreciated, these procedures require careful placement and manipulation of the distal portion of the catheter at a particular cardiac cavity. The noted patents describe use of a pair of tension/compression members to orient the axially spaced electrodes in a desired configuration. Generally, and without intending to be a complete synopsis of these patents, a low manual actuation force allows a user to selectively deflect a distal portion of the catheter into a desired form of curvature, for example, into the form of a loop or lariat as also taught in commonly owned U.S. application Ser. No. 726,235, published as 2002-0065514 A1, the disclosure of which is also incorporated herein by reference. The first and second tension/compression members act in concert to provide a desired radius of curvature of the distal portion of the catheter for monitoring purposes. In this manner, the electrodes provided on the distal portion are configured in a desired curvature (for example, a loop) and the assembly can be used for effective cardiac monitoring or mapping and ablation procedures.
The tension/compression members preferably include flattened portions adjacent to what is termed a kinematic junction. That is, as one of the members or wires is placed in tension, the other acts in compression to provide a smooth, controlled deflection of the distal portion. An actuator, such as a delta-shaped (Δ-shaped) actuator shown and described in the '024 patent, is located at the opposite or proximal end portion of the catheter assembly and cooperates with the pair of tension/compression members. By means of a pair of coupled sliders, selective articulation of the actuating member results in deflection of the distal portion of the catheter in one direction or another to form the desired curvature. Thus, the structure is able to curl in a plane substantially perpendicular to the length of the catheter and can deflect or curl in opposite directions depending on the direction of movement of the actuator.
In certain instances, additional bending of the curved (curled) distal portion or loop is required. This would enhance the performance in which the electrophysiology/ablation catheter could be used, and would also provide greater, desired control of its movement. The additional bending feature, however, has been difficult to achieve because of the limited volume or available space within the catheter assembly. This limitation also relates to the available space within the catheter assembly including the catheter handle as a result of the existence of electrical wires extending through the length of the catheter to communicate between the handle at the proximal end of the catheter and the electrodes disposed at the distal end. Moreover, the deflection means or deflection assembly in other prior art arrangements has heretofore been of such size that it limits the use or incorporation of additional components into the catheter assembly.
Accordingly, a need exists for additional, controlled bending feature of the catheter assembly without losing any of the benefits and advantages offered by those shown and described in the commonly owned patents and application.